What are the NB building code requirements for concrete driveway thickness?

The NB Building Code does not actually specify minimum thickness requirements for residential concrete driveways — driveways are not regulated structural elements under the building code in the way that foundations and load-bearing structures are. However, industry standards, material performance requirements, and the realities of New Brunswick's climate establish very clear de facto minimums that any reputable NB concrete contractor will follow.

The industry standard for a residential concrete driveway in NB is 5-6 inches (125-150 mm) of concrete over a minimum 4-6 inch compacted granular base. A 4-inch slab is technically used in some markets but is not appropriate for NB conditions — the combination of vehicle loads, frost heave, and freeze-thaw cycling makes 4-inch residential driveways more prone to cracking and displacement. The additional cost of going from 4 to 5 inches is relatively small (roughly 25% more concrete), while the durability improvement is substantial.

For driveways that will see heavier vehicle traffic — frequent delivery trucks, RVs, or heavy pickup trucks — 6 inches is the appropriate minimum. Commercial driveways and any surface that may be accessed by fully loaded concrete or delivery vehicles should be 6-8 inches with #15M rebar on 12-inch centres rather than wire mesh.

The granular base is as important as the slab thickness. NB's frost heave cycle means the ground beneath a driveway is moving every winter. A properly compacted granular base (crusher run or clear stone) of 4-6 inches minimizes differential heaving by providing free drainage and a stable bearing surface. Driveways poured directly on poorly drained clay or organic soil, regardless of thickness, will heave and crack. In areas of Moncton and Fredericton with heavy clay soils, the base preparation is as critical as the concrete specification.

Reinforcement requirements: wire mesh (6x6 W1.4/W1.4) or #10M rebar on 12-18 inch centres is standard for NB driveways, supported on chairs at mid-slab height. Control joints should be cut or tooled every 8-10 feet to manage cracking location — without them, the slab will crack on its own schedule, usually not where you'd choose.

What the code does govern is the driveway approach — where the driveway meets the municipal road. Approach grades, sight lines, and drainage are regulated by the municipality and, for provincial roads, by the NB Department of Transportation and Infrastructure. This connection point requires a permit in most cases. New Brunswick Concrete can connect you with driveway contractors experienced in NB conditions across Moncton, Fredericton, Saint John, Bathurst, Miramichi, and beyond.